Predicting postoperative day 1 hematocrit levels after uncomplicated hysterectomy

OBJECTIVE: To develop a model for predicting postoperative hematocrit levels after uncomplicated hysterectomy. METHODS: In a retrospective study, data were analyzed from the Michigan Surgery Quality Collaborative for non-emergent hysterectomies performed for benign indications among women aged at least 18 years between January 1, 2012, and April 4, 2014. Linear mixed models were used for univariate and multivariate analyses. RESULTS: The model was developed with data from 4747 hysterectomies and validated on 1184 cases. In the mixed multivariate analysis, higher postoperative day 1 (POD1) hematocrit levels were associated with higher weight (B=0.03222, P<0.001), higher preoperative hematocrit (B=0.6587, P<0.001), and non-vaginal hysterectomy (B=0.2815, P=0.0055). Lower POD1 hematocrit was associated with higher preoperative platelet count (B=-0.00457, P<0.001), greater estimated blood loss (B=-0.00652, P<0.001), and larger intraoperative crystalloid volume (B=-0.3303, P<0.001). The final model predicted POD1 hematocrit within 4% points of the actual value for 91.7% of cases in the validation set. CONCLUSION: Use of the model after uncomplicated hysterectomy might help to support the practice of selectively conducting postoperative hematocrit tests after hysterectomy in a clinically thoughtful and cost-effective manner.